Femtosecond dynamics of electronic states in the Mott insulator 1T-TaS2 by time resolved photoelectron spectroscopy

摘要: Photoexcitation of the Mott insulator 1T-TaS2 by an intense laser pulse leads to ultrafast transition toward a gapless phase. Besides collapse electronic gap, sudden excitation charge density wave (CDW) mode results in periodic oscillations states. We employ time resolved photoelectron spectroscopy monitor rich dynamics electrons and phonons during relaxation equilibrium. The qualitative difference between oscillatory CDW monotonic recovery gap proves that is indeed insulator. Moreover quasi-instantaneous build-up mid states contrast with retarded response expected from Peierls insulating Interestingly, photoinduced midgap spectral region display weak resonance reminiscent quasiparticle peak.